1. Field of the Invention
This invention relates generally to an elevator climbing system, and more particularly concerns a portable elevator climbing system removably attachable to a cantilevered overhang on an adjacent structure, wherein an elevator car travels up and down a plurality of roller chains.
2. Description of the Related Art
Elevators, trams and other devices for transporting items and people up and down steep slopes and vertically through buildings are known. There has always been a danger that, should the device fail, the elevator car or tram would fall a great distance resulting in damage to goods and death to passengers. Several devices have been designed to operate as brakes to stop a rapidly descending car or tram upon failure of the elevator device.
These devices are designed to detect when an elevator car or platform accelerates passed a predetermined speed. The device then rapidly stops the elevator car. This sudden stop jerks whatever is in the car and can cause damage to products and injure passengers. In addition, the car may be stopped at an inconvenient spot. An elevator may be caught between floors and a tram may be stopped only halfway down its track and difficult to get to.
Known elevators also typically use a rack and pinion system, which must be precisely aligned, or may utilize a traction belt, which is adapted to engage a drive pulley. The traction belt must be attached to a hoistway ceiling and be tensioned on the other end by a spring or other tensioning weight. Further, the traction belt is typically engaged to a drive sheath about 180° thus having a total effective wrap angle of about 360° on each side. With this high total effective wrap angle, the traction belt will become increasingly hot, thus, increasing its chance of failure, slippage and breaking. The traction belt suffers from a high wear rate.
Known elevators also typically require counterweights to aid in the lifting a specific load and these counterweight drive system may only be used in straight vertical lifts, allowing only for a finite alignment options. These counterweight drive systems are only usable indoors or in a machine room for an elevator, and may not be utilized in all weather conditions, including but not limited to sleet, rain or snow. If these counterweight drive systems or systems using traction belts are used outside in sleet, rain or snow, acclimate weather would cause the belt to slip and wear, thus, not allowing adequate lifting capacity.
It is therefore desirable to provide a portable elevator climbing system capable of being removably attached to a cantilevered overhang on an adjacent structure.
It is also desirable to provide an elevator climbing system having an elevator car that travels up and down a plurality of roller chains.
It is further desirable to provide an elevator climbing system having roller chains engaged with sprockets and guide rollers, which are attached to an axle driven by a motor.
It is yet further desirable to provide an elevator climbing system wherein the orientation and alignment of the sprockets, guide rollers and roller chains provide for a stable elevator car and for a system free of backlash in both directions.
It is yet further desirable to provide an elevator climbing system having a dampening assembly to control the rate of decent in the event of transmission, motor or other failure.
It is yet further desirable to provide an elevator climbing system that may be controlled so that the start and stop of the motor is coordinated with the release and application of a braking assembly.
It is yet further desirable to provide an elevator climbing system having variable efficiency by adjusting the offset between the sprockets and the guide rollers.